The present invention relates to refrigerated merchandisers, and specifically to dual temperature refrigerated merchandisers that condition low and medium temperature product display areas.
Existing refrigerated merchandisers typically include a case that defines one or more display areas accessible by consumers from the front of the case. Some merchandisers include doors that enclose the product display area. The display area is cooled by a refrigeration system that includes an evaporator assembly and a condenser assembly arranged in a circuit, and a fan distributes cooled air toward the product display area. In some merchandisers, the condenser and evaporator assemblies are positioned separate and remote from each other within the refrigerated merchandiser. In some cases, the refrigeration system is modular and can be removed from the merchandiser as a unit. For example, U.S. Pat. No. 7,703,295, assigned to Hussmann Corporation, describes and illustrates a merchandising display cooler that includes an accessible compartment for receiving a removable refrigeration unit, the refrigeration unit including both an evaporator assembly and a condenser assembly.
Typically, the product display area of existing merchandisers is maintained within a predetermined temperature range that depends on the type of product to be cooled. For example, a low temperature merchandiser typically maintains the product display area at temperatures less than 32 degrees Fahrenheit, whereas a medium temperature merchandiser typically maintains the product display area at temperatures between 33-41 degrees Fahrenheit. Often, existing merchandisers include either a low temperature refrigeration system or a medium temperature refrigeration system.
In some existing low temperature merchandisers, the product display temperature provided by the low temperature refrigeration system is adjusted via electronic control to a temperature that is warmer than the low temperature range for which the refrigeration system is designed. However, product in the product display areas of these merchandisers frequently freezes due to very cold discharge air upon startup of the low temperature refrigeration system. That is, because these low temperature refrigeration systems frequently use a large compressor, which is designed to lower the suction temperature to accommodate the low temperature range, air discharged into the product display area is much colder than desired when trying to use the low temperature system in this manner.
While some of these systems incorporate a suction pressure regulating valve in addition to a solenoid valve to avoid frozen product, these systems are typically manually actuated. Also, regardless of how existing systems try to avoid frozen product, use of low temperature refrigeration systems to accommodate a product display temperature associated with a medium temperature merchandiser significantly lowers the efficiency of the merchandiser and necessitates additional components and complex controls.